You can also read the extended essay guide here. Start reading from page 6 because the first bit is ToK blab. Then skim until page 15, which is the start of the Assessment Criteria. Then skip to page 34 for Biology, 43 for Chemistry and page 96 for Maths (yay!), which also has sample questions.

Some archived articles from Significance magazine. These vary in themes from physics and politics to zombies.

You might be able to get an idea for a pure maths exploration by solving a problem. Some good problems to struggle with can be found here, as well as in past maths challenges or olympiads. You would have to go beyond the problems, but they could be interesting starting points.

If you want to do some original statistical analysis, xkcd has just released masses of data from its survey.